Automated assembly device to tolerate blade variation

ABSTRACT

An automated device facilitates the assembly a surgical instrument that includes a knife with a high aspect ratio. The automated device includes a fixture for restraining a subassembly of the surgical instrument that includes the knife. A blade grip on the device is movable relative to the fixture, and is configured to urge the knife into a restrained position in the subassembly suitable for the subsequent assembly of an additional instrument component. A grip actuator is provided to move the blade grip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication Ser. No. 61/041,130 entitled “AUTOMATED ASSEMBLY DEVICE TOTOLERATE BLADE VARIATION” filed Mar. 31, 2008 by Jim Cunningham et al,which is incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to a device for assembling a surgicalinstrument. In particular, the device automates certain steps of anassembly process to ensure components of the instrument are properlyaligned and connected.

2. Background of Related Art

Many surgical instruments include a blade or knife for mechanical tissuecutting. Often these knives are positioned at a distal end of theinstrument and are operable from a proximal location on the instrumentto traverse a particular path through the tissue. This arrangement maybe particularly evident in surgical instruments configured for minimallyinvasive surgery. In a minimally invasive surgical procedure, a narrowtube or cannula may be inserted through a small incision made in apatient to provide access to a surgical site. Surgical instrumentsconfigured for minimally invasive surgery are thus typically equippedwith an elongate shaft coupling a working head at the proximal end ofthe instrument to the end effector at the distal end of the instrument.The knife typically forms a component of the end effector, and controlsurfaces for activating the knife are typically located on the workinghead. Positioning the elongate shaft through the cannula thus permits asurgeon to manipulate the knife at an internal surgical site from thecontrol surfaces that remain on the exterior of the patient.

To facilitate this remote operability, an aspect ratio of the knife maybe relatively high, i.e., the geometry of the knife may be long andnarrow. A knife exhibiting a long and narrow geometry may tend to bend,warp or otherwise deviate from a flat or straight configuration. Thesedeviations may be relatively random such that each knife manufactured toa particular specification is distinct from other such knives, and thesedistinctions may present difficulties in defining an assembly procedurefor instruments including the knives.

Typically, a knife may be manually assembled with other instrumentcomponents such as a support structure or knife guide. The knife guidemay have an opening configured to receive the knife such that the knifemay be visually aligned and threaded through the opening. The knifeguide may be subsequently assembled into the instrument with the knifeprotruding from the opening. Such a process is labor intensive andpresents various opportunities for error and damage to the instrumentcomponents. For example, a manually assembled knife could be damaged byunintended contact with the knife guide. Accordingly, the assembly of asurgical instrument may be facilitated by an assembly device thatautomates certain steps of the assembly process while accounting forvariations in blade geometry.

SUMMARY

The present disclosure describes an automated device, which mayfacilitate the assembly a surgical instrument that employs a knife witha high aspect ratio. The automated device includes a fixture forrestraining a subassembly of the surgical instrument that includes aknife. A blade grip on the device is movable relative to the fixture,and is configured to urge the knife into a restrained position in thesubassembly suitable for the subsequent assembly of an additionalinstrument component. A grip actuator is provided to move the bladegrip.

The grip actuator may be configured to move the blade grip in a lateraldirection relative to the subassembly, and the device may furthercomprise at least one tapered finger extending in the lateral direction,such that a leading portion of the tapered finger encounters the knifein an unrestrained position and a trailing portion of the tapered fingerencounters the knife in the restrained position. The blade grip may beconfigured to urge the knife toward the restrained position in avertical direction relative to the subassembly, and the grip actuatormay include a pneumatic slide.

The device may further include a component block configured to restrainthe additional assembly component, and the component block may bemoveable in a longitudinal direction relative to the fixture toapproximate the additional assembly component and the subassembly. Thedevice may also include a knife block configured to move relative to thefixture to define a longitudinal position of the knife within thesubassembly.

According to another aspect of the disclosure, a device for facilitatingthe assembly of a surgical instrument may include a fixture forrestraining a subassembly of the surgical instrument including a knife,a knife block moveable in a longitudinal direction relative to thefixture to define a longitudinal position of the knife within thesubassembly, and a component block configured to restrain an additionalassembly component. The knife block and the component block may beconfigured for concurrent movement to facilitate assembly of theadditional assembly component to the subassembly.

The knife block and the component block may also be selectivelyconfigured for selective independent movement relative to one another.The device may include a blade grip, which is moveable in a lateraldirection to define a vertical position of the knife within thesubassembly. The device may further include a jaw block for restraininga jaw member to be installed onto the subassembly, the jaw blockmountable relative to the fixture such that the jaw member operablyengages the knife upon movement of the knife block.

According to still another aspect of the disclosure, a method ofassembling a surgical instrument including a knife includes may includeloading a subassembly of the instrument that includes the knife into afixture such that the knife is movable within the subassembly, advancinga blade grip to urge the knife to a restrained position within thesubassembly, approximating an additional instrument component relativeto the subassembly to constrain the additional instrument componentwithin the subassembly, and moving the instrument component and theknife concurrently to install the additional instrument component.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is an perspective view of a surgical instrument that may beassembled by the processes and devices described herein;

FIG. 2A is an exploded, perspective view of a distal portion of theinstrument of FIG. 1 including a knife having a long and narrow geometryand a knife guide for affecting movement of the knife;

FIG. 2B is a close up view of the end effector of FIG. 2A;

FIG. 2C is a partial, perspective view of the end effector of FIG. 2B inan assembled and closed configuration depicting the knife in an extendedposition;

FIG. 2D is a top, cross-sectional view of the end effector of FIG. 2Cdepicting the knife in a retracted position;

FIG. 2E is a side, cross-sectional view of the end effector of FIG. 2Din an open configuration;

FIG. 3 is a perspective view of an assembly device in accordance withone embodiment of the present disclosure;

FIG. 4 is a perspective view of the assembly device of FIG. 3 having asafety cover removed to reveal forward and rear interior regions of theassembly device;

FIG. 5 is a close up, perspective view of a portion of the forwardinterior region;

FIG. 6 is a flow chart summarizing a method for assembling theinstrument of FIG. 1 using the assembly device of FIG. 3;

FIGS. 7A through 7C depict steps of the method summarized in FIG. 6wherein components of the instrument including the knife and knife guideof FIG. 2A are manually loaded into the assembly device;

FIGS. 8A and 8B depict steps of the method wherein automated movementthe assembly device constrains the knife;

FIGS. 9A through 9D depict steps of the method wherein automatedmovement of the assembly device constrains and installs the knife guide;and

FIGS. 10A through 10C depict steps of the method wherein a pair of jawmembers are assembled onto the instrument.

DETAILED DESCRIPTION

The devices and processes of the present disclosure may facilitateaccurate assembly of a surgical instrument such as an electrosurgicalforceps 10. A more detailed description of the assembly and operation offorceps 10 may be found in commonly assigned U.S. Patent ApplicationPublication No. 2007/0078456 to Dumbauld et al. The attached figuresillustrate exemplary embodiments of the present disclosure and arereferenced to describe the embodiments depicted therein. Hereinafter,the disclosure will be described in detail by explaining the figureswherein like reference numerals represent like parts throughout theseveral views

Referring initially to FIG. 1, the electrosurgical forceps 10 includes adistal end 12 and a proximal end 14. An end effector 18 near the distalend 12 is configured to manipulate tissue at a surgical site byclamping, electrosurgically energizing, cutting and/or otherwisecontacting the tissue. Two jaw members 22, 24 of the end effector 18 areconfigured to move between an open position as shown in FIG. 1, in whichthe distal-most ends are substantially spaced and a closed positionwherein the distal most ends are closer together. The end effector 18 iscoupled to an elongate shaft 26. Elongate shaft 26 facilitates the useof forceps 10 in a minimally invasive surgical procedure, wherein theelongate shaft 26 is inserted through a cannula as discussed above. Atthe proximal end of forceps 10 is a working head 28 including severalcontrol surfaces, which a surgeon uses to remotely manipulate the endeffector 18. For example, handles 30 may be drawn together toapproximate jaws 22, 24 or drawn apart to separate jaws 22, 24. Othercontrol surfaces may include a knob 32, which may be used to rotate theend effector 18, buttons 34, 36, which may be used to initiate variousmodes electrosurgical energy delivery to the jaws 22, 24, a slide 38,which may be used to control the intensity of electrosurgical energydelivered, and trigger 40, which may be used to advance a knife 42 (FIG.2A) through tissue clamped by jaws 22, 24.

Referring now to FIG. 2A, an arrangement of a distal portion of forcepsassembly 10 is described that permits a surgeon to operate end effector18 from the proximal end 14 of the forceps 10. Within elongate shaft 26,several components are arranged in a generally concentric relation andmoveable relative to one another in order to transmit motion from theproximal end 14 to the end effector 18. For example, a drive sleeve 50is received within elongate shaft 26 in a manner permitting the drivesleeve 50 to longitudinally translate or reciprocate relative to theelongate shaft 26. A rotating shaft 54 is similarly received within thedrive sleeve 50 such that the drive sleeve 50 may reciprocate relativeto the rotating shaft 54. A knife bar 58 is received within the rotatingshaft 54 such that the knife bar 58 may reciprocate relative to therotating shaft 54. A knife 60 is coupled to a distal end of the knifebar 58, such that the knife 60 reciprocates along with the knife bar 58.The knife 60 may be attached to the knife bar 58 in any suitable way,e.g., snap-fit, fiction-fit, pinned, welded, glued, etc.

A knife guide 62 is supported in the rotating shaft 54 and remainsstationary with respect to the rotating shaft 54. Knife guide 62 may bepress fit into an opening in the distal end of the rotating shaft 54 andincludes a tapered interior channel therein (see FIG. 9C) to receiveknife 60. The knife guide may thus urge knife 60 into a central positionwithin the rotating shaft 54 and ensure proper alignment of knife 60 asit reciprocates within upper and lower jaw members 22, 24 (see FIG. 2D).Knife guide 62 may also serve to protect the knife 60 and othercomponents from damage throughout the assembly process as will bedescribed in greater detail below.

A pivot pin 66 and a drive pin 68 are included to operatively associatethe upper and lower jaws 22, 24 to both drive sleeve 50 and rotatingshaft 54. An insulating boot 70 is positioned over a distal end of thedrive sleeve 50 and a portion of upper and lower jaws 22, 24. The boot70 may be formed from a flexible or resilient material such that theboot 70 may accommodate the movement of upper and lower jaws 22, 24 asthe jaws are approximated and separated.

Referring now to FIG. 2B, jaw member 22 is equipped with a proximalflange 72 and jaw member 24 is equipped with a proximal flange 74. Eachof the proximal flanges 72, 74 includes a pivot hole 76 to receive pivotpin 66 and a drive slot 78 to receive drive pin 68 therein. The pivothole 76 and the drive slot 78 are configured to permit appropriaterelative motion of the jaw members 22, 24 about the pivot pin 66 anddrive pin 68. Drive sleeve 50 and rotating shaft 54 are each equippedwith a bifurcated distal end to accommodate the proximal flanges 72, 74of jaw members 22, 24. Drive sleeve 50 includes a bore 80 extendingthrough both portions of its bifurcated end, and similarly, rotatingshaft 54 includes a bore 84 extending through both portions of itsbifurcated end. Bores 80, 84 are configured to fixedly retain respectivepins 66, 68 therein by a press-fit or similar connection. Rotating shaft54 also includes a longitudinal slot 86 extending through both portionsof its bifurcated end. Longitudinal slot 86 is configured to accommodatelongitudinal movement of drive pin 68 there through. Knife 60 alsoincludes an elongate slot 90 that permits knife 60 to reciprocatewithout interfering with pins 66, 68.

When fully assembled, pivot pin 66 is positioned through bore 84, pivotholes 76 and elongate slot 90 to permit the jaw members to pivot aboutthe pivot pin 66. Drive pin 68 is positioned through bore 80,longitudinal slot 86, drive slots 78, and elongate slot 90. As depictedin FIGS. 2C and 2D, this arrangement provides for a closed configurationof jaw members 22, 24 (jaw member 22 and boot 70 are removed forclarity) in which drive slots 78 are oriented in general alignment witha longitudinal axis of the instrument 10. When jaw members 22, 24 are inthe closed configuration, drive pin 68 is disposed in a proximalposition within the drive slots 78 and within longitudinal slot 86. Ifthe drive sleeve 50 is caused to move in a distal direction with respectto the rotating shaft 54, drive pin 68 moves distally within the driveslots 78 toward pivot pin 66. This motion causes the drive slots 78 tomove to an oblique orientation out of the general alignment with thelongitudinal axis of the instrument 10. Thus jaw members 22, 24 aremoved into an open configuration as depicted in FIG. 2E. In this openconfiguration, drive pin 68 assumes a distal position within the driveslots 78. Imparting an opposite relative motion between drive sleeve 50and rotating shaft 54, i.e., moving drive sleeve 50 proximally, when thejaw members 22, 24 are in the open configuration serves to move the jawmembers to the closed configuration. Handles 30 are configured such thatmanipulation of the handles 30 effects relative motion between the drivesleeve 50 and rotating shaft 54 to move jaw members 22, 24 between theopen and closed configurations.

If knife bar 58 is caused to move distally with respect to the rotatingshaft 54, knife 60 is advanced into the jaw members 22, 24 as depictedin FIG. 2C. Elongated slot 90 in the knife 60 permits this motionwithout interference from pins 66, 68. Trigger 40 is configured suchthat manipulation of the trigger 40 effects motion of the knife bar 58to effect advancement of the knife 60.

As can be appreciated, the functionality of instrument componentsdescribed above may require an intricate assembly process. Each of theinstrument components must be properly positioned and oriented in amanner appropriate for a particular step in the assembly process. Such aprocess may be difficult to accomplish manually as access to aparticular instrument component may be limited once the component isinstalled. Also, any variations in the knife 60 from an entirelystraight and flat configuration may further complicate the assemblyprocess. Accordingly, an automated assembly device may facilitate theassembly of the electrical forceps 10 and other instruments that requirecomplicated assembly of components, e.g., a surgical stapler.

Referring now to FIG. 3, an automated assembly device in accordance withthe present disclosure is depicted generally as 100. Assembly device 100includes a base plate 102, that may be configured to be placed on atable-top or other structure to provide an operator convenient access toa forward interior region 104 of the device 100. A hinged safety cover106 is provided to selectively enclose the forward interior region 104,and to protect the operator during various stages of an assembly processin which automated movement occurs. An interlock 108 is mounted withinthe forward interior region 104 such that a key 110 mounted on thesafety cover 106 is approximate to the interlock 108 when safety cover106 is in a closed configuration (not shown). A controller (not shown)is included and configured to permit automated movement when safetycover 106 is in a closed configuration, and disable automated movementwhen safety cover 106 is in an open configuration. Thus, the operatormay safely load, unload and manipulate instrument components when safetycover 106 is open.

Removing safety cover 106 reveals a rear interior region 112 of theassembly device 100 as depicted in FIG. 4. A quick-disconnect coupling114 provides a pneumatic input for compressed air provided by anexternal source to enter device components housed in the rear interiorregion 112. For example, coupling 114 may communicate with devicecomponents such as an air pressure regulator 116 or valve bank 118.Components of the assembly device, to which access less frequentlyrequired, may be housed in the rear interior region 112. Regulator 116,for example, may require adjustment only once to provide a suitable airpressure for the assembly device 100, and thereafter many forceps 10 orother instruments may be assembled using the device 100.

Extending from regulator 116 is a pneumatic fitting 120. Pneumaticfittings 120 or similar fittings are operatively connected to fluidconduits (not shown) to provide fluid communication between componentsof assembly device 100. Such fluid conduits are used to delivercompressed air to the forward interior region 104 of the device 110through either one of gates 122. Gates 122 are equipped with tie-downanchors 124 attached to the base plate to facilitate organization of thefluid conduits. Tie down anchors 124 may be located at various locationsthroughout the assembly device 100 and provide an opening through whicha cable tie or other restraint may be secured.

The forward interior region 104 houses four main device components orassembly blocks, which are used to restrain or manipulate instrumentcomponents within the assembly device 100. These include a fixture 130,a knife block 132, a component block 134, and guide block 136. A fifthdevice component, jaw block 138, is removable from the assembly device100 to conveniently load smaller instrument components such as jawmembers 22, 24 as described in greater detail below.

The four main assembly blocks 130, 132, 134, 136 are arranged asdepicted in FIG. 4 to define an initial configuration wherein eachassembly block is located in an initial position with respect to thebase plate 102. Fixture 130 is centrally located within the forwardinterior region 104 and is fixedly mounted to the base plate 102. Knifeblock 132 is mounted to an actuator or carrier component such asprecision pneumatic slide 150. Pneumatic slide 150 is configured toselectively advance knife block 132 from an initial position in alongitudinal direction with respect to fixture 130 as indicated by arrow“A.” Pneumatic slide 150 may be retracted to return knife block 132 toan initial position. Component block 134 is mounted to pneumatic slide152, and pneumatic slide 152 is mounted to pneumatic slide 154.Pneumatic slide 152 is configured to selectively advance component block134 in a longitudinal direction with respect to pneumatic slide 154 asindicated by arrow “B.” Pneumatic slide 154 is configured to selectivelycarry component block 134, pneumatic slide 152, and a guide block 136together in a longitudinal direction with respect to the base plate 102as indicated by arrow “C.” Guide block 136 is mounted to a pneumaticslide 156, which is configured to selectively carry guide block 136 in alateral direction with respect to the base plate 102 as indicated byarrow “D.” Each of the pneumatic slides 150, 152, 154, and 156 are alsoconfigured to selectively return the assembly blocks 130, 132, 134, 136to respective initial positions.

Referring now to FIG. 5, fixture 130 includes a shaft reception channel160 across a top surface thereof. Shaft reception channel 160 isconfigured to receive a slender instrument component such as rotatingshaft 54 therein, and a pair of toggle clamps 162 is provided to securethe instrument component within the channel 160. A sensor housing 168 isdisposed on an end of fixture 130 such that a narrow channel 170 acrossa top surface thereof may receive a distal portion of the instrumentcomponent. Narrow channel 170 is in general alignment with channel 160,and is adjustable to precisely define the location of the distal end ofthe instrument. Sensor housing 168 supports jaw block 138 in areleasable manner on an end opposite of channel 160, and houses a sensor172 (FIG. 9C), which is configured to detect the presence of jaw block138 as described in greater detail below.

Component block 134 includes a guide mount 174 projecting therefrom uponwhich the knife guide 62 may be mounted. The guide mount 174 includes athin tongue 176 configured to extend into an interior region of theknife guide 62 in order to support the knife guide 62 thereon. A leadingface 178 of the guide mount 174 provides a stop for mounting knife guide62 and leading face 178 enables the guide mount 174 to press the knifeguide 62 into position within the rotating shaft 54 upon longitudinaltranslation of component block 134 during an assembly process describedbelow.

Component block 134 also includes a bumper post 180, which limits thetravel distance of component block 134. Bumper post 180 extends fromcomponent block 134 in the direction of fixture 130 to define a minimumdistance therebetween. Alternatively, bumper post 180 may extend fromfixture 130 in the direction of component block 134.

Guide block 136 is bifurcated including two complementary components. Atleast one of the components of assembly block 136 includes a blade grip182 (see FIG. 8A) that supports the knife 42 during an assembly processdescribed below. Blade grip 182 may be configured to accommodate bladedeviations or variances to facilitate the assembly process.

Also visible in FIG. 5 is a control surface 190. Control surface 190 maytake the form of a push button, and may be electrically coupled to thecontroller (not shown) to perform a variety of functions. For example,control surface 190 may be configured to advance and retract guide block136, or alternatively provide an emergency stop for the assembly device100.

Referring now to FIG. 6, an assembly process for the distal end offorceps 10 is summarized in which certain steps are automated to accountfor variations or deviations in knife 60. An initial preparatory step,which precedes the process outlined in FIG. 6, may be to manually removejaw block 138 and retain the jaw block 138 for use in later assemblysteps. Many of the other steps summarized in FIG. 6 are described ingreater detail below with reference to FIGS. 7A though 10C.

An initial assembly step is to manually preassemble some of theinstrument components before loading into the forward interior region104 of assembly device 100. For example, the knife 42 may be fixedlypreassembled to knife bar 58 by pinning, welding or any otherappropriate means. Once the knife 60 is coupled to the knife bar 58, theknife bar 58 is manually inserted into the rotating shaft 54 in a mannerpermitting longitudinal translation there between as described above. Asubassembly of instrument components is thus be defined by thisarrangement of the knife 60, knife bar 58, and rotating shaft 54.

Once these components have been preassembled into a subassembly, theymay be loaded into the assembly device 100. As depicted in FIG. 7A, therotating shaft 54 is positioned to rest in the shaft reception channel160 of fixture 130. Toggle clamps 162 are arranged to fix the positionof the rotating shaft 54 relative to the stationary fixture 130. Theknife bar 58 extends from rotating shaft 54 such that the rotating shaft54 is separately restrained in knife block 132 as depicted in FIG. 7B.Knife block 132 includes a post 192 projecting there from to provide alocating and orienting mechanism for knife bar 58. Post 192 permits onlya single orientation of knife bar 58 and thus ensures knife bar 58 isproperly oriented. A locating pin 194 is installed through aprefabricated hole (visible in FIG. 2A) to fix the location of knife bar58 relative to knife block 132. This arrangement provides for thereciprocation of knife bar 58 along with knife 42 within rotating shaft54 at such time pneumatic slide 150 may be activated.

As depicted in FIG. 7C, knife guide 62 is loaded onto component block134 before any automated movement occurs. Knife guide 62 is positionedonto the tongue 176 until the knife guide 62 abuts leading face 178. Atthis point, with rotating shaft 54, knife bar 58, knife 60, and knifeguide 62 loaded into the assembly device 100, the safety cover 106 isclosed and automated movement may be initiated.

Pneumatic slide 154 is initially activated or extended to deliver guideblock 136 into proximity to fixture 130 and sensor housing 168 asdepicted in FIG. 8A. Knife 60 projects into the bifurcated end ofrotating shaft 54 due to the positioning of the proximal end of knifebar 58 in the knife block 132. Knife block 132 remains at a retracted orinitial position thus defining the longitudinal position of the knifebar 58 and knife 60 within rotating shaft 54. The knife 60 may deviatefrom a central position between the two portions of the bifurcated endof the rotating shaft 54 due to blade variations, tolerance buildups, orother concerns. In particular, the knife 60 may be disposed off centerin a vertical direction such that subsequent assembly of instrumentcomponents is complicated.

To ensure that the knife 60 is not damaged upon the assembly ofsubsequent instrument components, pneumatic slide 156 is activated todeliver guide block 136 from a retracted position to an extendedposition to restrain knife 60. As depicted in FIG. 8B, blade grip 182 onguide block 136 includes a pair of opposed tapered fingers with inclinedsurfaces that urge knife 60 into a central disposition as guide block136 is extended in a lateral direction. A leading portion of the taperedfingers may encounter the knife 60 in an unrestrained position and atrailing portion of the tapered fingers may encounter the knife 60 inthe restrained position. Thus a vertical position of knife 60 may bedefined. Once knife 60 is centrally disposed, knife guide 62 may besafely constrained.

Knife guide 62 is constrained by temporarily positioning the knife guide62 between the two portions of the bifurcated end of rotating shaft 54as depicted in FIG. 9A. Pneumatic slide 152 is activated and moved to apartially extended position to deliver the knife guide 62 to thebifurcated end of rotating shaft 54. Since the blade grip 182 maintainsthe knife 60 in a central disposition, the distal tip of the knife 60avoids contact with the knife guide 182 and any damage resulting therefrom. Once constrained, knife guide 62 partially encloses a distal tipthe knife 60.

Next, pneumatic slide 156 is activated to return guide block 136 to aretracted position and release knife 60 from the blade grip 182 asdepicted in FIG. 9B. With the knife 60 protected within knife guide 62,the knife guide 62 may be fully installed. Pneumatic slide 150 isextended concurrently with the further extension of pneumatic slide 152.The extension of pneumatic slide 150 will cause knife block 132 to drawknife bar 58 from rotating shaft in a proximal direction, and thus drawknife 60 in a proximal direction. The further extension of pneumaticslide 152 will move knife guide 62 proximally until knife guide 62 ispressed into position in rotating shaft 54. This concurrent movement mayprotect knife 60 from any damage that may result from contact withinterior walls of knife guide 62. As depicted in FIG. 8C, the distal tipof knife 60 remains protected within the knife guide 62 throughout thisassembly step.

With knife guide 62 installed, pneumatic slides 152 and 154 areretracted returning 134 and 136 to their retracted positions. Pneumaticslide 150 remains extended as depicted in FIG. 9D such that knife block132 remains in an extended position and knife 60 remains in a proximalposition within knife guide 62 for the next assembly step.

As depicted in FIG. 10A, jaw block 138 is manually loaded with jawmembers 22, 24. A transfer pin 196 is positioned between two locatingpegs 198 on jaw block 138 to locate and orient the jaw members 22, 24.Transfer pin 196 includes a lower pin portion configured to be receivedwithin pivot holes 76 or drive slots 78 in the proximal flanges 74 ofjaw members 22, 24. When transfer pin 196 is installed, jaw members 22,24 are properly arranged for assembly onto rotating shaft 54.

Safety cover 106 may be opened, and jaw block 138 pre-loaded with jawmembers 22, 24 may be installed into the assembly device 100. Asdepicted in FIG. 10B, jaw block 138 includes a pair of locating prongs202, which are received in a corresponding pair of holes in the sensorhousing 168. Transfer pin 196 is removed prior to installation of jawblock 138 to allow proximal flanges 72, 74 of jaw members 22, 24 to bemove between the two portions of the bifurcated distal end of rotatingshaft 54.

As depicted in FIG. 10C, sensor housing 168 includes a sensor such asproximity switch 172 configured to detect the presence of jaw block 138.When jaw block 138 is installed and proper alignment of the jaws, 22, 24is confirmed, proximity sensor 172 sends an appropriate signal to thecontroller. When safety cover 106 is closed and the appropriate signalhas been received, the controller permits pneumatic slide 150 toretract, thereby advancing knife bar 58 and knife 60 in a distaldirection into jaw members 22, 24.

The knife 60 is advanced until the longitudinal slot 68 therein issituated between pivot holes 76 in the proximal flanges 72, 74 of thejaw members 22, 24. The safety cover 106 may then be opened, andtransfer pin 196 is replaced. When replaced, transfer pin 196 ispositioned through bore 84, or longitudinal slot 86 in the rotatingshaft 54. As transfer pin 196 is replaced, the lower pin portion oftransfer pin 196 will extend through the longitudinal slot 68 in theknife 60, thereby temporarily coupling the knife 60 to jaw members 22,24.

This arrangement facilitates the manual installation of pivot pin 66into pivot hole 84, and drive pin 68 into bore 80, thus capturing jawmembers 22, 24 and knife 60. Manual installation of the boot 70 maycomplete the assembly of the distal portion of forceps 10. The distalportion is subsequently assembled with working head 28 to complete theforceps 10.

The process described above involves the use of pneumatic slides 150,152, 154, and 156 to automate certain steps of the assembly process.Other automated actuators may be substituted for one, or any number ofthe pneumatic slides 150, 152, 154, and 156 such as servo or stepmotors. Alternatively, manually prompted movement is contemplated. Forexample, the step of restraining knife 60 within blade grip 182 may beaccomplished manually. Guide block 136 may be configured to permitmanual motion to slide blade grip 182 over knife 60. Control surface 190may also be configured to facilitate any manual or semi-automaticmovement.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A method of assembling a surgical instrumentincluding a knife, the method comprising the sequential steps of:loading a subassembly of the surgical instrument that includes a knifeinto a fixture such that the knife is movable within the subassembly;advancing a blade grip to urge the knife to a restrained position withinthe subassembly; positioning a knife guide relative to the subassemblyto constrain the knife guide within the subassembly; and moving theknife guide and the knife concurrently in a non-rotational manner in afirst direction to install the knife guide.
 2. The method of assemblinga surgical instrument including a knife of claim 1, further comprisingthe step of: prior to the advancing step, closing a safety coverprovided to protect an operator.
 3. The method of assembling a surgicalinstrument including a knife of claim 2, further comprising the step of:providing a controller configured to permit automated movement when thesafety cover is in a closed configuration, and disable automatedmovement when the safety cover is in an open configuration.